How "difficult" is a Google search? I got 883,000 hits and it took 0.21 seconds. The author's clear implication is that the issue is imaginary, which is quite simply a falsehood.
The author calls on us to "just chill out," but I'm afraid ignoring the problem isn't going to make it go away. Controlled immigration is the sign of a healthy country. Uncontrolled immigration is its death knell.
The author is a typical lib journalist. Just because his moral relativism doesn't see a problem doesn't mean there isn't one. Starting with breaking US law the minute one crosses the border illegally.